A. Field of the Invention
The present invention relates to an apparatus and method for initializing an optical recording media. The present invention also relates to an initializing apparatus for changing an amorphous recording layer of an optical disc into a crystal recording layer. The invention may be used to manufacture phase-change optical recording media. The present invention also relates to a system for verifying uniform crystallization of phase-change optical recording media.
B. Description of the Related Art
In optical recording discs with rewrite capability, such as a CD-RW phase-change optical recording disc, a first dielectric layer, a recording layer, a second dielectric layer and a metal layer are formed on a disc substrate. The substrate is generally made of polycarbonate. A UV hardening layer may be provided on the metal layer.
The phase-change recording material of the CD-RW optical disc transitions into either (1) a crystal condition by lengthening the cooling time after it has been heated, or (2) an amorphous condition by shortening the cooling time after it has been melted. Phase-change recording media can record information in the form of marks by reversibly changing between the crystal condition and the amorphous condition. A recording signal can be used to change the intensity of the optical beam that is radiated on the recording layer to change the recording layer from a crystal condition to an amorphous condition, or vice versa. When forming marks, the optical beam intensity may be set at the amorphous level. On non-mark portions, the intensity of the optical beam intensity is set at the crystal level, and the recording layer is crystallized. Since non-mark portions are not heated as much and cool slowly, they transition into the crystal condition regardless of whether they were in an amorphous condition or in a crystal condition.
On the other hand, when manufacturing phase-change recording media, the recording layer is left in an amorphous condition after spattering. Therefore, it is necessary to crystallize all of the recording layer. This crystallization process is called the initialing process. As mentioned above, the length of the cooling time effects the transition to either the crystal condition or the amorphous condition. When the cooling time is longer, the recording layer transitions into the crystal condition. When the cooling time is shorter, the recording layer transitions into the amorphous condition. Therefore, in the initializing process of the recording layer, an optical beam is radiated on the recording layer and the cooling time is made longer after raising the temperature of the recording layer.
Because the substrate is generally made from polycarbonate, it is possible to exceed the heat-resisting properties of the material if the entire surface is initialized simultaneously. The initializing process is generally carried out by radiating an optical beam on the optical recording media while rotating the optical recording media. Successive portions of the recording layer are crystallized as the radiating position is moved in the radial direction.
One problem with the above-described scanning system is that any instability in the optical beam can result in incomplete crystal portions on the recording layer. If there are incomplete crystal portions, problems with recording and reproducing signals are caused, and it is impossible to record and reproduce information accurately.
It is therefore an object of the present invention to provide an initializing method and apparatus for determining if a recording layer of a phase-change optical recording disc is uniformly crystallized.
It is another object of the present invention to provide an initializing method and apparatus that can uniformly crystallize a recording layer of a phase-change optical recording disc.
In one aspect of the invention, the intensity of light reflected off of the optical recording media is detected. Based on the intensity of the reflected light, a judgement is made as to whether the initializing condition is acceptable or not. According to this aspect of the invention, the light used for initializing may be radiated on a rotating phase-change optical recording medium. The radiating position of the light may be moved radially relative to the optical recording medium
In another aspect of the invention, the intensity of the reflective light of the optical recording media is detected and the driving power of an initializing light source is adaptively adjusted. The initializing light radiated by the light source may be based on the intensity of the reflective light.
In another aspect of the invention, the intensity of the reflective light off of the optical recording media is detected and the rotation speed of the optical recording media and the relative moving speed of the initializing light in the radial direction of the optical recording process is adjusted as a function of the intensity of the reflective light. The intensity detection and speed adjustment steps may occur during the initialization process.
In another aspect of the invention, an initializing apparatus comprises: a driving means that drives an initializing light source for radiating the initializing light on optical recording media; a rotating means for rotating the optical recording media; a moving means for moving the radiating position from the initializing light source against the optical recording media in a radial direction; a detecting means for detecting the intensity of the reflective light of the optical recording media in initializing action of the optical recording media; and an analyzing means for determining if initializing conditions are acceptable or not based on the detected intensity of the reflective light.
In another embodiment of the invention, an initializing apparatus comprises: a driving means which drives an initializing light source for radiating the initializing light on optical recording media; a rotating means for rotating the optical recording media; a moving means for moving the radiating position from the initializing light source against the optical recording media in a radial direction; a detecting means for detecting intensity of the reflective light of the optical recording media in initializing action of the optical recording media; and an adjusting means for adjusting the driving power of the initializing light source based on the detected intensity of the reflective light of the optical recording media.
In another embodiment, an initializing apparatus comprises: a driving means which drives an initializing light source for radiating the initializing light on optical recording media; a rotating means for rotating the optical recording media; a moving means for moving relatively the radiating position from the initializing light source against the optical recording media in a radial direction; a detecting means for detecting the intensity of the reflective light of the optical recording media in initializing action of the optical recording media; and an adjusting means for adjusting a rotating speed of the optical recording media and the relative moving speed between the radiating position of the initializing light source and the optical recording media based on the detected intensity of the light reflected by the optical recording media.
In another aspect of the invention, the intensity of the reflective light is detected based on the reflection of the light radiated on the optical recording media.
In another aspect of the invention, the intensity of the reflective light is detected based on the reflection of the light radiated on the optical recording media by a second light source different from the light source used for initializing.
In another aspect of the invention, the intensity of the reflected light is determined and analyzed, the system responds accordingly, and the initialization process is repeated.
In another aspect of the invention, a determination is made as to whether the optical recording medium was inadequately initialized. The determination may be made during or after the initialization process.
In another aspect of the invention, the driving power of the initializing light source is monitored and actively adjusted to prevent poor initializing conditions.
In another aspect of the invention, the rotation speed of the optical recording media and the relative moving speed of the initializing light in the radial direction of the optical recording media are actively adjusted to prevent poor initializing conditions.
In another aspect of the invention, optical focusing servo and tracking servo systems may be employed.
In another aspect of the invention, information on the reflective light intensity is obtained by an exclusive optical arrangement independent of the reflective optical arrangement for the focusing servo and the tracking servo. This feature may be used to improve the reliability of the reflective light intensity information.
In another aspect of the invention, to carry out an initializing process, an initializing light source radiates an initialization light on the rotating phase-change optical recording media, and the radiation position is moved relatively in the radial direction of the optical recording media. The intensity of the reflective light of the optical recording media is detected. Based on the detected result, a determination is made as to whether the initializing condition is acceptable or not. The intensity of the reflective light may be detected during or after the initializing process.
In another aspect of the invention, to carry out an initializing process, an initializing light from the initializing light source is radiated on the rotating phase-change optical recording media, and the radiation position is relatively moved in the radial direction of the optical recording media. The intensity of the reflective light of the optical recording media is detected, and the driving power of the initializing light source is adaptively adjusted based on the detected result to prevent poor initializing conditions.
In another aspect of the invention, an initializing light from the initializing light source is radiated on the rotating phase-change optical recording media, and the radiation position is relatively moved in the radial direction of the optical recording media. The intensity of the reflective light of the optical recording media is detected, and the rotating speed of the optical recording media and the relative moving speed of the initializing light in the radial direction of the optical recording media are adaptively adjusted based on the detected result to prevent poor initializing conditions.
With these and other objectives, advantages and features of the invention that may become apparent, the nature of the invention may be more clearly understood by reference to the following detailed description, the appended claims, and the accompanying drawings.